SALMONELLO­SIS

EQUUS - - Eq Tack & Gear -

dis­eases which are com­monly as­so­ci­ated with lepto,” says Lin­ton. There seems to be a ge­netic com­po­nent to sus­cep­ti­bil­ity to ERU---the dis­ease is more preva­lent in Ap­paloosas than in other breeds.

When it af­fects the uterus of a preg­nant mare, lep­tospiro­sis can cause abor­tion late in ges­ta­tion. “And since lepto abor­tions are likely un­der­re­ported---mean­ing a de­fin­i­tive di­ag­no­sis was not made---we prob­a­bly un­der­es­ti­mate how sig­nif­i­cant a prob­lem this is,” says Gre­nager. In some cases, the foal may be born alive but very sick with lep­tospiro­sis. “The fe­tal flu­ids and pla­cen­tal flu­ids are in­fec­tive,” says Lin­ton. “If an­other horse comes into con­tact with these flu­ids this is an­other way the dis­ease can be trans­mit­ted.”

Kid­ney dis­ease from lep­tospiro­sis isn’t com­mon in horses, but some do de­velop acute re­nal fail­ure. A kid­ney in­fec­tion may re­sult in shed­ding of the pathogen via urine. “Even af­ter the in­fec­tion is un­der con­trol, the horse may con­tinue to shed bac­te­ria for sev­eral weeks,” Lin­ton says. “Since the bac­te­ria can be passed in the urine, it’s im­por­tant to iso­late any horse with an ac­tive kid­ney in­fec­tion.”

If the lep­tospiro­sis is still in the acute stage of in­fec­tion, your vet­eri­nar­ian will treat it with the ap­pro­pri­ate an­tibi­otic. “There are dif­fer­ent an­tibi­otic rec­om­men­da­tions based on the body sys­tem that the bac­te­ria hap­pens to be af­fect­ing,” says Gilse­nan. “Your vet­eri­nar­ian will recommend the ap­pro­pri­ate treatment.”

Like­wise, other treat­ments will de­pend on the body sys­tem af­fected. For ex­am­ple, says Gre­nager, “a horse with kid­ney fail­ure will also need sup­port­ive care and lots of flu­ids.” Treatment can­not help a mare who has al­ready aborted, but af­fected foals born alive may re­spond to an­tibi­otics. In both cases, the horses may need to be kept iso­lated for up to 16 weeks with pe­ri­odic tests to make sure they are not shed­ding bac­te­ria in their urine.

ERU is dif­fi­cult to treat ef­fec­tively be­cause it is more than just a sim­ple bac­te­rial in­fec­tion---the dis­ease, which can ap­pear two to eight months af­ter the ini­tial lep­tospiro­sis in­fec­tion, is an au­toim­mune dis­or­der. Al­though how Lep­tospira or­gan­isms cause ERU isn’t fully un­der­stood, it ap­pears that the pro­teins on L. pomona are sim­i­lar enough to pro­teins found in the tis­sues within the eye to cross-re­act with the an­ti­bod­ies. In other words, the an­ti­bod­ies cre­ated to fight the pathogen end up at­tack­ing the body’s own tis­sues as well.

“One of the things that com­pli­cates ther­apy is that of­ten it’s not sim­ply the or­gan­ism that causes a prob­lem but rather the an­i­mal’s im­mune re­sponse to the or­gan­ism, such as when an eye is dam­aged,” says Gilse­nan. “Part of the treatment in­volves qui­et­ing down the in­flam­ma­tion in the eye with some kind of cor­ti­cos­teroid, and an­other com­po­nent is us­ing an an­tibi­otic that will pen­e­trate into the eye.”

• Vac­ci­nate. In late 2015, Zoetis in­tro­duced the first vac­cine against lep­tospiro­sis ap­proved for use in horses. “The new vac­cine has only been out for a short time, but Zoetis did rig­or­ous safety tri­als and an ef­fi­cacy trial that showed it works,” says Gre­nager. “It is la­beled as ef­fec­tive against L. pomona.”

In con­trolled tri­als, the vac­cine pre­vented lep­tospiremia---the pres­ence of the bac­te­ria in the blood­stream--af­ter ini­tial ex­po­sure. It is be­lieved that re­duc­ing the in­fec­tion in the blood­stream re­duces the risk of the com­pli­ca­tions as­so­ci­ated with lep­tospiro­sis---ERU, kid­ney dis­ease or abor­tion.

• Ad­just man­age­ment prac­tices to min­i­mize ex­po­sure. “It is bet­ter to not feed hay on the ground. It also helps if you can min­i­mize ar­eas of stand­ing wa­ter, which is help­ful in pre­vent­ing many other prob­lems as well,” says Gre­nager. Keep wa­ter troughs and buck­ets clean, and fence off ac­cess to ponds, marshy ar­eas and other nat­u­ral wa­ter sources.

“If a mare aborts, you need to test for lepto and if the test is pos­i­tive, treat and iso­late her un­til proven that she is no longer shed­ding bac­te­ria,” Gre­nager says. “All the aborted tis­sues should be re­moved and the area dis­in­fected ap­pro­pri­ately.”

A com­mon cause of di­ar­rhea in ma­ture horses, salmonello­sis is caused by Sal­monella en­ter­ica bac­te­ria. The most fre­quent method of trans­mis­sion for sal­monella is fe­cal-to-oral, mean­ing that the bac­te­ria are shed in ma­nure, then con­sumed with con­tam­i­nated feed or wa­ter. Strictly speak­ing, salmonello­sis isn’t solely a wa­ter-borne dis­ease, but it is passed eas­ily through con­tam­i­nated wa­ter---both in un­clean buck­ets and troughs as well as nat­u­ral ponds and streams.

“Sal­monella can be read­ily trans­mit­ted via wa­ter or hu­man hands and boots,

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